Feeding arrangement for metal spray gun



March 7, 1961 Filed March 3, 1959 A. F. HEDDE FEEDING ARRANGEMENT FORMETAL SPRAY GUN 2 Sheets-Sheet 1 INVENTOR.

JMOLL March 7, 1961 A. F. HEDDE 2,973,892

FEEDING ARRANGEMENT FOR METAL SPRAY GUN Filed March 3, 1959 2Sheets-Sheet 2 g 8 /o 5 /b /4l 7 Q 7b 9 w I M E W H0 2 INVENTQR. i MMFEEDING ARRANGEMENT FOR METAL SPRAY GUN Andr F. Hedda, Paris, France,assignor to Societe Nouvelle de Metallisaiion, Paris, France Filed Mar.3, 1959, Ser. No. 796,950

Claims priority, application France Mar. 4, 1958 2 Claims. (Cl. 226-484)The present invention relates to a feeding arrangement for feeding arod-shaped material to a pressurefluid operated atomizing gun, and moreparticularly to a feeding arrangement for feeding a fusible metallic rodor wire to a gun for melting; therein by the application of heat and forspraying of a jet of. molten atomized metal by a stream of gas underpressure.

In conventional guns of the type described above, the wire or rod is fedto a source of heat by two grooved pulleys arranged on substantiallyparallel respective shafts. Itv is usual to have both pulleys inpermanent engagement with a driving motor and to stop feeding of therod-shaped material to the source of heat in the gun by moving one ofthe pulleys away from the wire so as to relieve the pressure of thepulleys against the wire. In such an arrangement, one of the pulleys ismounted on a radially movable shaft while the other pulley is mounted ona shaft, the position of which is fixed.

It has been found that with such an arrangement, the friction betweenthe. pulley mounted on the fixedly positioned shaft and the rod-shapedmaterial is sufficient even after removal of the other pulley to causecontinued feeding of a certain amount of rod-shaped material after thecontrols of the spray gun have been set to interrupt spraying. 1

Since the controls for the source of heat in the gun and for thefeeding: mechanism are interlocked, an

atent f) 2, ment of the rod with the cooperating atomizing elements ofthe gun An additional object is a feeding arrangement which is securedagainst contamination by solid particles in the ambient atmosphere andis-thus not subject to wear by such. particles.

With these and other objects in View, the invention mainly consists in afeeding arrangement of the type generally described having a support, asource of. pressure fluid, two shafts mounted on the support andtwogrooved pulleys respectively mounted on the shafts'in such a manner thatrespective portions of the grooves of the pulleys face each other sothat a rod-likematerial may be clamped between the facing grooveportions. The feeding arrangement of the invention furthermore providesmeans for simultaneously rotating the pulleys, means responsive to thepressure of the pressure fluid for urging each of the shafts to move ina predetermined respective direction relative to the support in such amanner as to urge the facing groove portions of the pulleys toward aline fixed with respect to the support and amount of rod orwire-materialis fed into the gun after 7 the source of heat and the stream of.atomizing fluid have been discontinued; This material isnot fused. Itv

is wasted or may interfere with proper functioning of the: gun whenoperation is resumed.

Feeding of. rod-shaped material to the gun by two cooperating pulleys,one of which is mounted on a fixedly positioned shaft whereas the shaftof the other pulley is radially movable makes it diflicult or evenimpossible to operate such a gun with fusible materials of differentdiameter or with. a fusible material the diameter of which varies beyonda very close range of tolerances.

Proper functioning of the gun depends on very precise alignment of theaxis of the rod or wire of fusible material with the source of heat andwith the stream of atomizing fluid. A feeding arrangement having twopulleys mounted respectively on a fixedly and movably positioned shaftcauses a different axial position of the material. fed if the. diameterof the material varies or if. materials of different diameter areemployed.

A principal object of the invention is a feeding arrangement for arodshaped heat fusible material in an atomizing gun or. the likeoperated by a fluid under pressure in which feeding of the material isstarted and instantaneously stopped when flow of the pressure fluid isstarted and. interrupted respectively.

Another object is a feeding arrangement of the type described which. iscapable of accommodating rod-shaped material of varying diameter withoutdisturbing the aligntangential to each of the pulleys, and meanspermanently urging each of the shafts to move in a respective directionopposite to the'predetermined direction.

In its more specific aspects, the invention provides that the shaftscarrying the feed pulleys are in permanent engagement with drivingmeansand are each mounted in bearing members acted upon by a fluid underpressure by means of which the gun is operated so that the pulleys areurged against each other by the pressure of the fluid against: thebearing members for clamping the rod shaped material. Upon interruptionof the flow of the fluid, the pulleys are each moved away from therodshaped fusible material by a resilient member permanently urging themapart with a force insuflicient to overcome the force of the fluid underpressure. With such an arrangement, axial movement of the rod-shapedfusible material has been found to stop immediately when the flow of thepressure fluid is interrupted and the pres sure thereof is permitted todissipate. As soon as the flow of pressure fluid is'restored, thepulleys are urged against each other so as to clamp the fusible materialtherebetween and to feed it to the gun.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together I with additional objects and advantages thereof,will be best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

Fig. 1 is a side elevational view, partly in section, of a gun of thetype described equipped with the feeding arrangement of the invention;

Fig. 2 is a sectional view of a control valve for Operating theinventive feeding arrangement; and

Fig. 3 is a fragmentary sectional view of the gun of V Fig. 1 taken onthe line IIIIII.

Referring now to the drawings and more particularly to Fig. 1, there isshown a metal spraying gun for atomizing a rod-shaped fusible materialby a stream of gas after it was molten by a flame. The operating partsof the gun are enclosed in a housing 10 from which the spray nozzle 15projects. Three conduits 16, 17, and 0 18, respectively, supply acombustible fluid, a combuss tion supporting fluid, and an atomizingfluid to the gun.

Examples of suitable fluids are respectively propane, oxygen, andcompressed air, but the invention is not limited to any specific fluids,nor is it exclusively applicable'to metal spraying guns in whichreaction of a combustible fluid with a combustion supporting fluid isthe source of heat for melting a fluidizable rod-shaped material,

Flow of filuids from the conduits 16, 17 and 18 is simultaneouslycontrolled by a multiple rotary control valve in the housing 10 actuatedby a lever 19. The multiple valve also includes a valve elementcontrolling admission of the atomizing fluid to the feeding arrangement.An electric motor 20 is arranged in the housing 10 to supply drivingenergy to the feeding arrangement of the invention. Line current issupplied to the electric motor 20 by a cable 21. The fusible material 30which may be a metal wire is drawn into the housing 10 by the feedingarrangement of the invention through a guide tube 29.

Fig. 2 illustrates in radial cross section the element of the multiplerotary valve operated by the lever 19 which cooperates with the feedingarrangement of the invention. There is shown a .valve housing 22 formedwith three openings therein communicating respectively with theatomizing fluid conduit 16,. a forked conduit 3 and the atmosphere. Arotary valve plug 23 is mounted in the valve housing 22 for rotation by'means of the valve lever 19. The plug 23 has a T-shaped bore 24 whichpermits'connecting the forked conduit 3 either to the conduit 16 or tothe atmosphere.

Fig. 3 which shows a fragmentary sectional view of the gun of Fig. 1,illustrates the feeding arrangement of the invention which is mounted inthe housing 10. There is shown a support block 11 secured on the insideof the housing 10 and formed with a cylindrical bore 13. Two plungers 4and 4' closely fitting the bore 13 are axially movable therein betweenrespective end portions closed by plugs 28 and 28'. A shoulder 13ainwardly projects into the central portion of the bore 13 from thesupport plug 11. The plungers 4 and 4 are provided with circumferentialannular grooves 4a in which packing rings 5 are arranged for preventingleakage of fluid past the plungers from the end portions of the bore 13.The faces of the plungers 4 and 4' arranged opposite each other forabutment against the shoulder 13a are provided with axial recesses 4b inwhich respective ends of a compression spring 6 are retained so as tourge the plungers 4 and 4 to move away from each other.

The plungers 4 and 4 each have a bore transverse to the axis of the bore13 and communicating with corresponding bores in the support block 11.The shafts 7a and 7b are arranged in these bores with radial clearance.One respective end of the shafts 7a, 7b is supported in oscillatingbearings 2 and 2' mounted in the wall of the housing 10. Respectiveportions of the shafts spaced from the ends are supported in oscillatingbearings 12 and 12 mounted in the respective transverse bores of theplugs 4 and 4.

Grooved pulleys 1a and 1b are fixedly mounted on ends of the shafts 7aand 7b respectively which project outside the support block 11, and arefastened to the shafts by cap nuts 8. Resilient annular seals 14 and 14'are provided between circular surfaces of the pulleys 1a and 1b and theopposite outer surface of the support block 11 to prevent entry ofatmospheric contaminants such as solid particles of the material beingatomized into the interior of the support block 11.

The shafts 7a and 7b carry meshing gear wheels 9 which are of equaldiameter. At least one of the gear wheels 9 is in driving engagementwith a mating gear wheel (not shown) which is driven by the electricmotor 20.

The two end portions of the bore 13 in the support block 11 communicatewith respective ends of the forked conduits 3.

The aforedescribed device operates as follows:

The electric motor 20 is continuously running during working periods ofthe gun, that is, even when the gun is not in actual operation and theflow of the atomizing fluid is cut off. The shafts 7a and 7b are thuscontinuously driven by the gears 9 and the pulleys 1a and 1bcontinuously rotate. As long as the valve control lever 19 is in theinoperative position, the connection between the conduit 16 and theconduit 3 is interrupted by the valve plug 23. When the lever 19 isturned, fluids are permitted to flow through the conduits 16, 17 and 18,and atomizing fluid is admitted by the valve plug 23 through the forkedconduit 3 to the end portions of the bore 13 in the support block 11.The pressure of the atomizing fluid urges the plungers 4 and 4 towardseach other against the force of the compression spring 6. The pulleys 1aand 1b are thus moved toward each other so that a rod-shaped fusiblematerial positioned between facing portions of the grooves of thepulleys 1a and 1b is clamped therebetween and is fed by the rotatingpulleys towards the fusing and atomizing zones of the gun.

When the flow of atomizing fluid through the conduit 16 is interruptedby turning the lever 19, the valve plug 23 is simultaneously rotatedinto a position in which the forked conduit 3 communicates with theatmosphere and the pressure acting on the plungers 4 and 4 isdissipated. The force of the spring 6 returns both plugs to theirpositions close to the end portion of the bore 13. Since the position ofthe wire 30 between the pulleys 1a and 1b is substantially fixed by theguide tube 29, contact between the wire and both pulleys is brokenalmost instantaneously when the valve is turned and no unmolten materialis pushed past the source of heat during interruption of the sprayingprocess. It will be understood that each of the elements describedabove, or two or more together, may also find a useful application inother types of atomizing guns for spraying a fusible material differingfrom the types described above.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new annd desired to be secured by Letters Patent is:

1. In a feeding arrangement for feeding a rod-shaped material to apressure-fluid operated atomizing gun and the like, in combination, asupport; a source of pressure fluid; cylinder means mounted on saidsupport; two plunger means axially movable toward and away from eachother in said cylinder means between end portions thereof; rmilientmeans interposed between said plunger means to permanently urge the sameaxially away from each other; means for admitting pressure fluid fromsaid source simultaneously to said end portions of said cylinder meansfor urging said plunger means axially toward each other; a bearing ineach of said plungers; two shafts each mounted in one of said hearingsin said plungers; two pulleys respectively mounted on said shafts, eachof said pulleys having a peripheral groove, respective portions of thegrooves of said pulleys facing each other; means for simultaneouslyrotating said pulleys, said plunger means being responsive to thepressure of said pressure fluid for urging each of said shafts to movein a predetermined respective direction relative to said support in sucha manner as to urge said facing groove portions toward each other and tosaid resilient means for urging said shafts to move in a respectivedirection opposite to said predetermined direction, whereby a rodlikematerial may be clamped between said facing groove portions of saidpulleys for feeding during rotation of said pulleys while said pressureis applied to said plunger means.

2. In a feeding arrangement for feeding a rod-shaped material to apressure fluid operated atomizing gun and thelike, in combination, asupport; a source of pressure 76 fluid; two shafts mounted on saidsupport each turnable about the axis thereof and each pivotable about apoint located on the axis of the respective shaft adjacent one endthereof; two pulleys respectively fixedly mounted on said shaftsadjacent the other ends thereof, each of said pulleys having aperipheral groove facing each other at adjacent portions thereof; a pairof gears respectively fixedly mounted on said shafts adjacent at one endthereof, said gears meshing with each other; means operatively connectedto one of said gears for rotating the same to simultaneously rotate saidshafts; means responsive to the pressure of said pressure fluid forurging each of said shafts to pivot in a predetermined respectivedirection about said pivot points relative to the support in such amanner so as to urge said facing groove portions toward each other; andmeans permanently urg- 15 ing each of said shafts to pivot in arespective direction opposite to said predetermined direction, whereby arod- References Cited in the file of this patent UNITED STATES PATENTSHammon Nov. 21, 1939 2,655,066 Siegerist Oct. 13, 1953 2,660,471 Egly eta1. n Nov. 24, 1953 FOREIGN PATENTS 118,627 Germany Mar. 20, 1901

